# G2S_SetBlendAlpha

## C Specification

      #include <nitro/gx/g2.h>

      void G2S_SetBlendAlpha(
          int plane1 /* GXBlendPlaneMask */,
          int plane2 /* GXBlendPlaneMask */,
          int ev1,
          int ev2
      );

## Description

Alpha blending will be performed using the sub 2D Engine if the second target plane immediately follows the first target plane. Alpha blending will be performed for translucent OBJ, bit map OBJ, and 3D planes, even if OBJ is not specified in the first target plane.

`GX_BLEND_PLANEMASK_NONE` | Does not specify any plane
`GX_BLEND_PLANEMASK_BG0` | Specifies BG0
`GX_BLEND_PLANEMASK_BG1` | Specifies BG1
`GX_BLEND_PLANEMASK_BG2` | Specifies BG2
`GX_BLEND_PLANEMASK_BG3` | Specifies BG3
`GX_BLEND_PLANEMASK_OBJ` | Specifies OBJ
`GX_BLEND_PLANEMASK_BD` | Specifies a backdrop plane

The following are the type definitions for the `GXBlendPlaneMask` type.

    typedef enum
    {
        GX_BLEND_PLANEMASK_NONE = 0x0000,
        GX_BLEND_PLANEMASK_BG0 = 0x0001,
        GX_BLEND_PLANEMASK_BG1 = 0x0002,
        GX_BLEND_PLANEMASK_BG2 = 0x0004,
        GX_BLEND_PLANEMASK_BG3 = 0x0008,
        GX_BLEND_PLANEMASK_OBJ = 0x0010,
        GX_BLEND_PLANEMASK_BD = 0x0020
    }
    GXBlendPlaneMask;

## Arguments

`plane1` | Selects the first blend target plane (it is a logical OR of the values of the `GXBlendPlaneMask` type)
`plane2` | Selects the second blend target plane (it is a logical OR of the values of the `GXBlendPlaneMask` type)
`ev1` | The alpha-blending coefficient for the first target plane
`ev2` | The alpha-blending coefficient for the second target plane

## Return Values

None

## See Also

`G2S_BlendNone, G2S_SetBlendBrightness, G2S_SetBlendBrightnessExt, G2S_ChangeBlendAlpha, G2S_ChangeBlendBrightness`

## Revision History

02/09/2004 Initial Version